Nutrition & hydration

Nutrition is the most argued-about topic in health, and most of the arguments are about the edges: keto or vegan, fasting or grazing. At the centre, the evidence is surprisingly consistent. Eat mostly whole foods, plenty of plants and fibre, enough protein, and not too much of anything.

Five principles

1. Mostly whole foods. Diets high in ultra-processed foods, products made mostly from industrial ingredients with long lists of additives, are linked with higher risk of heart disease, type 2 diabetes, depression and early death. In a controlled trial, people offered an ultra-processed diet ate around 500 more calories a day than when offered a minimally processed one, without meaning to.

2. Enough protein. Protein maintains muscle, and muscle is a longevity organ. The official minimum is 0.8 g per kg of body weight per day. For active adults and anyone over 50, 1.2–1.6 g/kg is a better target. Spread it across meals, around 30 g each, and start the day with some.

3. Lots of fibre. Most Europeans eat around 20 g a day. A large 2019 review for the WHO found the biggest benefits at 25–29 g or more, with risk of heart disease, stroke, type 2 diabetes and bowel cancer continuing to fall at higher intakes. Aim for 30 g or more, from vegetables, fruit, legumes, whole grains, nuts and seeds. Increase slowly and drink water with it.

4. The right fats. Olive oil, nuts, oily fish and avocado over processed and fried foods. Oily fish twice a week covers most people's omega-3 needs.

5. Not too much. Excess fat, especially around the waist, drives inflammation and insulin resistance. You don't need to count calories forever, but if your waist is a red box you do need to eat a little less than you burn.

What to limit

• Sugary drinks and juice. The easiest calories to cut.
• Processed meat. Classified by the WHO's cancer agency as a cause of bowel cancer.
• Alcohol. No level is good for your health. Less is better, and none is best for sleep.

A simple plate

Half vegetables or salad. A quarter protein: fish, eggs, poultry, tofu, legumes or lean meat. A quarter slow carbohydrates: potatoes, whole grains, beans. A drizzle of olive oil. That's most of it.

When you eat

Time-restricted eating, eating within an 8–10 hour window, works for some people mainly because it cuts down on snacking. Controlled trials show little benefit beyond eating the same amount at any time of day. What's clearer: a large, late dinner hurts sleep. Finish eating 2–3 hours before bed.

Hydration

The European Food Safety Authority recommends about 2.0 litres of total water a day for women and 2.5 litres for men, with roughly 70–80% coming from drinks and the rest from food. You need more in the heat and when you exercise. The simplest check is pale yellow urine. Water, tea and coffee (before noon) all count.

Key numbers
1.2–1.6 g/kg: daily protein for active or older adults.
30 g+: daily fibre.
2.0–2.5 L: total daily water (EFSA).

This week

• Add protein to your breakfast.
• Add one serving of beans, lentils or chickpeas on three days.
• Swap one sugary or alcoholic drink a day for water or sparkling water.
• Write your three food rules: your protein target, your last-food time, and one thing you'll stop buying.

In the journal

The "Nutrition" box is judged against three rules you set once, before day one, not against a perfect diet.

Sources: Hall et al., Cell Metabolism 2019 · Reynolds et al., The Lancet 2019 · EFSA, Dietary Reference Values for water, 2010 · IARC Monographs volume 114, 2018